What a match this should be!

I've not the slightest clue what's going on with Del Potro. I've still not got the slightest how he beat Federer here in 2009, let alone a concept of what it took to beat Thiem the other day. And today, he was just closer to his best than Federer, serving better and more consistently, playing big points well, and hauling himself back into that crucial third set when it looked like momentum had shifted for good. It's true that Federer wasn't at it today, unable to find his usual consistency of brilliance, but Del Potro is a wonderful player, a majestic competitor and clearly a very sound lad. The way he has fought back from injury is inspirational and moving, and his match against Nadal will be a jazzer - join us for that, and for the woen's semis tomorrow. Night!

HUGE SERVE OUT WIDE, MURDEROUS FOREHAND, AND THAT'S A STUNNING PERFORMANCE FROM A COLOSSAL, MONUMETAL HUMAN BEING! HE SPREADS HIS ARMS AGAIN, SALUTES THE CROWD, AND WILL MEET RAFAEL NADAL ON FRIDAY!

Federer chips a second serve back, charges, and has to stretch for the volley, missing by a fair bit. Match point Delpo!

Even rally, great defence from Federer to reflect the power back, and Del Potro goes long! 30-all!

But here we go! Federer dips a return just over the net, Delpo can't do much with it, and Federer whacks a backhand that he can only divert into the net.

An ace. Byeeee.

Del Potro has lost one point on serve this set, but his first effort is wide ... it doesn't matter. Federer hits himself into the rally, so Del Potro finishes it with a forehand winner. Of course he does.

At 0-15 Del Potro slams a forehand at Federer, stood at the net ... he ducks and the ball lands in! You what! But Federer is not giving this up and quickly goes up 40-30 before floating a backhand down the line and onto the outside of it. Del Potro will have ti serve for it...!

Del Potro is not going to give this away, ramming home his 11th ace at 130mph for 30-0. so Federer tries to chip a return, getting nowhere, and can't get his next effort back into play. Del Potro is one game away!

Federer tries to play himself back into things, a backhand slide drop from behind the baseline giving him 30-0. He holds to 15, but knows that this is not the real quiz.

Federer gets the first point of the next game, but Del Potro simply sends down a second serve ace, an especially ballsy move given the double faults that have contributed to his being broken. What a man he is. And he's soon at 40-15, then seals the game with a raking bastard down the T.

Ey up, Del Potro gets to 15-30 and it looks for a second as though Federer has gone! He hits a tame forehand, and faces two break points! He doesn't get a first serve, but he does get that forehand going, twice! Twin sons of bitches down the line get him to deuce, and he bellows a come on because he thinks he's back. But he's not! He misses an overhead from on top of the net, when Delpo had no business playing a lob; what on earth is going on?! AND WHAT'S THAT! A TAME SERVE, A BOOMING BACKHAND CROSS-COURT OF A RETURN, AND SUDDENLY THIS IS NEARLY DONE!

Del Potro is looking very strong, his serve and groundstrokes working in harmony. Federer, on the other hand, is still not happy with his forehand down the line, which is affecting his confidence and decision-making. Another easy hold.

Another rapid hold, the chaps calming down in readiness to amp up again.

Del Potro is absolutely buzzing his titties off here, and shmices down a love game.

Federer holds easily. Perhaps that will calm him.

ARE YOU KIDDING ME! AFTER FOUR SET POINTS IN HIS FAVOUR AND RESPONDING TO A BRILLIANT RETURN, FEDERER'S VOLLEY IS LONG AND THE MOST FLUCTUATING, FLUCTUATINGEST, MOST FLUCTUATINGEST SET I'VE EVER SEEN IS DEL POTRO'S! HE'S ONE AWAY!

Del Potro is wild and doubles ... Federer has another set point! he serve volleys, but Del Potro keeps calm and hits chest high to force the error. This set is now an epic, this breaker is now an epic, a mash of brilliance and human weakness ... Del Potro saves another set point with a mighty forehand then arranges one of his own with feline agility at the net, albeit on Federer's serve.

Del Potro goes long on the forehand and after what seems like seven hours and seven minutes, Federer has two set points ... Del Potro saves the first, responding to a fine serve with a sweeping forehand return down to the ankles and onto the line ... and the second with a ferocious serve. My days.

There is not one single fly on this pair of badasses, and at 4-2 a strong forehand gets Delpo the mini-break back and the oles begin. He responds with a violent serve, but then nets a forehand, and Federer is back in charge!